Former US president Donald Trump is selling Bibles ahead of the Easter holiday, encouraging his supporters to "Make America Pray Again" and buy what he describes as his "favorite book."

The 77-year-old Republican presidential candidate, who counts conservative Evangelical Christians among his staunchest supporters, is selling the Bibles -- which contain the unusual addition of the US Constitution and the Declaration of Independence -- for $59.99.

Trump, who unlike most US presidents rarely attends church except during public political events, has advertised the Bibles, which feature a cover embossed with an American flag, during what Christians call Holy Week.

The move is part of a partnership with country music singer Lee Greenwood, whose song "God Bless the USA" is a well-established Trump rally anthem.

In a three-minute video posted on his Truth Social network on Tuesday, Trump told supporters that "Christians are under siege" as he hawked a large-print King James Version of the Bible complete with what he called America's "founding father documents."

"Religion and Christianity are the biggest things missing from this country," he said, compelling viewers to "protect content that is pro-God. We love God."

"All Americans need a Bible in their home and I have many -- it's my favorite book," he said, telling supporters: "We must Make America Pray Again" in a play on his campaign slogan "Make America Great Again."

None of the revenue from the Bibles will be used to finance the Trump campaign, according to the website where they are sold, which indicates the former president's image is being used as part of a paid partnership.

The video was posted as the real estate mogul's Trump Media & Technology Group, which includes Truth Social, soared in its Nasdaq debut.

Trump launched Truth Social after he was kicked off mainstream social media platforms following the January 6, 2021 attack on the US Capitol by a mob of his supporters.

The former president is facing a huge bond payment after a New York court ruled that he, his sons and their family business lied for years about the value of his assets.

On Monday, a New York appeals court cut the $454 million bond payment that had been due to $175 million, and gave him 10 extra days to pay.

Trump was widely criticized by religious leaders in 2020 after posing for a photo, Bible in hand, in front of a church near the White House just minutes after security forces forcefully ejected peaceful protesters from the area. The church had been defaced with graffiti and damaged in a fire during previous demonstrations.

Trump is far and away preferred by conservative Christians over President Joe Biden, a practicing Catholic who regularly attends mass.